1. Field of the Invention
This invention relates to devices known as particle separators that remove sand and extraneous matter from air entering gas turbine engines and more particularly to an improved vane within a collection chamber of a particle separator for such an engine.
2. Background of the Prior Art
Aircraft gas turbine engines are particularly susceptible to damage from foreign objects introduced into air inlets of the engines. The problem has been most acute in the past with respect to relatively large foreign objects such as stones, gravel, birds and hail.
With the advent of gas turbine powered helicopters and other verticle takeoff and landing (VTOL) aircraft, smaller particles of foreign matter such as sand and water have become increasingly troublesome due primarily to the conditions under which such VTOL aircraft are frequently operated. The advantage of VTOL capability makes such aircraft particularly useful in areas where conventional air fields do not exist, frequently occurring in combat zones and other isolated areas. VTOL aircraft are also specially suited for certain low-altitude missions over both land and sea. Under these and other similar conditions, substantial quantities of small foreign objects such as sand and water may become entrained in intake air supplied to the gas turbine engine. These foreign particles, which individually have relatively little effect on the engine, can cause very substantial damage when ingested into the engine in large quantities.
As an example, recent experience has shown that engines in helicopters operating at low altitude in a desert environment can lose performance very rapidly due to erosion of the engine blading by the ingestion of dust and sand particles. Similar problems can occur when operating over salt water because of heavy ingestion of salt-water droplets which can cause both corrosion and destructive erosion of turbine structures.
In attempting to solve this problem, various particle separator systems have been developed for use with gas turbine engines. One example of a successful system is disclosed in U.S. Pat. No. 3,832,086--Hull, Jr., et al. In this disclosure, a separator system is shown with a collection chamber into which extraneous matter is directed with centrifugal forces. While the advantages of such a system are numerous, it has been found that particles entering the collection chamber will sometimes strike certain flat surfaces and be caused to bounce back into the flow stream of air entering the engine's core. Regurgitation of extraneous matter in this fashion can work to reduce the efficiency of the particle separator system.
It is, therefore, an object of the present invention to provide an improved engine inlet particle separator wherein separation efficiency is increased by reducing the volume of particles which are rebounded back into a core engine inlet after first entering a separate collection chamber area.
It is another object of the present invention to provide collector flowpath vanes that operate to scavenge and retain extraneous matter entering a collection chamber of the separator and prevent such extraneous matter from regurgitating back into the core engine flow stream.